Artificial dielectric material mixed with randomly distributed conductive fibres is a well-known composition.
However, various problems exist affecting dielectric losses in conventional artificial dielectric material mixed with randomly distributed conductive fibres. FIG. 1 (Prior Art) illustrates randomly distributed conductive fibres 102 in a conventional artificial dielectric material. As shown in FIG. 1, the distribution of the fibres in the material is not uniform, some parts of the material consist of more conductive fibres than other parts. Also, after mixing, some conductive fibres make contact with one another to create conductive clusters 104. Each cluster may consist of a different number of fibres. The overall effect of fibres and other fibres or clusters having different distances apart and non-uniform concentrations of fibres is an increase in dielectric losses in the material.
In the complex representation of the permittivity of a dielectric material, ∈″ represents the imaginary part of the permittivity of the material, which is related to the rate at which energy is absorbed by the material (converted into thermal energy, etc.). Hence, ∈″ is a measure of dielectric losses in a dielectric material. The response of dielectric materials to external electromagnetic fields generally depends on the frequency of the field. In order to achieve small losses (i.e. small ∈″) at a required frequency for dielectric material mixed with conductive fibres, it is necessary that the length of the fibres in the dielectric material be much smaller compared to the wavelength at the required the frequency.
The creation of clusters affects uniformity, anisotropy, and increases the dielectric losses of the material by increasing the resonance width of ∈″. When fibres make contact with each other, it is equivalent to increasing the length of the fibres. This increase in length undesirably leads to the shifting of resonance losses to a wide frequency range, in particular, the lower frequency range. In addition, with fibres and clusters having different distances apart, the frequency width of resonance losses is further increased. All these problems also lead to the amplification of dielectric losses in a wide frequency band, in particular, the lower frequency range, and can affect the fabrication of dielectric materials for devices such as dielectric lenses, dielectric antennas etc.
Conventionally, low loss dielectric materials for instance, solid blocks of polystyrene, polyethylene, or the like, in use are relatively heavy in weight. For some applications of the dielectric materials, such as dielectric antennas, being heavy is considered an undesirable feature.
A need therefore exists to provide an artificial dielectric material that addresses at least one of the above-mentioned problems.